Thursday, June 12, 2008

More Masai

I left out one of the juicier tidbits from the last post because it was getting long. Investigators Kang-Jey Ho et al. wanted an explanation for why the Masai didn't have high serum cholesterol despite their high dietary cholesterol intake (up to 2,000 mg per day-- 6.7 times the US FDA recommended daily allowance).

They took 23 male Masai subjects aged 19 to 24 and divided them into two groups. The first group of 11 was the control group, which received a small amount of radioactive cholesterol in addition to a cholesterol-free diet that I will describe below. The second group of 12 was the experimental group, which they fed 2,000 mg cholesterol per day, a small amount of radioactive cholesterol as a tracer, and the exact same cholesterol-free diet as the control group. For the duration of the 24-week trial, the subjects ate the experimental diet exclusively. Here's what it was (in order of calories, descending):
  • Nondairy coffee creamer (made of corn syrup solids and vegetable oil)
  • Beans
  • Sugar
  • Corn
  • Corn oil
  • A vitamin pill
Not a healthy diet by most peoples' standards, but those items are nevertheless widely eaten in the US. Over the course of the 24-week study, the investigators found no difference in serum cholesterol between the control and experimental groups. This isn't really surprising. The body has mechanisms for regulating blood cholesterol, and if you aren't eating any it just synthesizes more to stay at its preferred level.

The really interesting thing is that serum cholesterol increased dramatically in
both groups. It went from 125 mg/100 mL to over 170 mg/100 mL, despite a large decrease in the saturated fat they were eating. The change took about two weeks to occur, and remained fairly stable for the remainder of the trial.

Both groups also gained weight. In the first week, they gained an average of
3 pounds each. To be fair, the initial gain was probably most water, which is what happens when a person increases their carbohydrate and salt intake. The investigators freaked out and cut their calorie intake by 400 kcal, only allowing them 3,600 kcal per day. Initially, they were voluntarily consuming 4,000 kcal per day. I find that interesting as well. Something tells me they weren't chugging non-dairy creamer because it was so delicious, but because their confused hormones were telling them to EAT.

Even after putting the subjects on calorie restriction (not letting them eat as much as they wanted, by an average of 400 kcal/day), they continued gaining weight. By the end of the study, the 23 subjects had gained an average of 7.8 lbs per person.

To summarize, this is what the investigators saw when they put 23 unfortunate Masai men on a bottom-rung industrially processed diet: elevated cholesterol, hyperphagia (excessive eating), and weight gain. Sounds familiar, doesn't it?


Christopher Robbins said...

You should read these links on the Masai.


Stephan Guyenet said...

Thanks Chris,

The first link is by the authors of the study I described in the post. I think it's interesting that they blame their low cholesterol on genetics; they did that in the paper too. It's a nice fallback when your results are inconvenient.

In retrospect, we now know that eating cholesterol doesn't raise blood cholesterol in most people, just like in the Masai and the Inuit. Eating eggs for example, which are very rich in cholesterol, doesn't budge your blood cholesterol.

Christopher Robbins said...

In all fairness, they give valid reasons for their assumptions. I've never studied the masai or any nearby HGs so I have to take their word. Is it true the men stop being so active around age 24? Other points of the article include nearby tribes who eat basically the same meat/milk/blood yet have higher cholesterol. To top it off, the one Masai who lives in the US also has low cholesterol. If all those statements are true, a genetic component is quite possible. We all know high/low cholesterol in most people is genetic based. Nothing new there. We also know high/low cholesterol means nothing when it comes to predicting cardivascular disease. People with high cholesterol live to 100 while people with low cholesterol have heart attacks and vice versa. So it's neither here nor there.

Christopher Robbins said...

Have you heard a couple of months ago about the Maasai running the London Marathon. You can check that out at They tell a little history of the Maasai such as them possibly being a lost Roman legion. Also, they say how they live off of mostly blood and milk. Rarely eating cow except on special occasions for traditional ceremonies as cows are their "money" and "bank accounts".

Christopher Robbins said...

On other sites dedicated to the Maasai they talk about how "more recently, the Maasai have grown dependent on food produced in other areas such as maize meal (unga wa mahindi), rice, potatoes, cabbage (known to the Maasai as goat leaves), etc." I'd like to see the results of new studies to see how this new diet is impairing their health.

Stephan Guyenet said...


I agree with you that total cholesterol doesn't really correlate with CVD or total mortality risk, I just think it's interesting that the diet increased it, along with the weight. Normally, saturated fat is supposed to be what increases blood cholesterol but this demonstrated the reverse. It may be that sat fat only increases cholesterol against the backdrop of a Western diet.

There may be a genetic component to cholesterol levels, but I think lifestyle is the more potent factor. For example, Japanese who immigrate to the US get American cholesterol values. Also remember that the Masai are actually a genetically diverse population; many of them are descended from agriculturalists because the Masai traditionally raid nearby tribes for women.

About the nearby tribes with higher cholesterol, I guess you mean the Samburu. Yes, they do have higher cholesterol, but I don't know enough about them to say why. It may simply have been access to more processed food. You can see that the Masai's cholesterol shoots up when they go off the Muran period and have access to processed food, the same way it shoots up when they are fed processed food under controlled conditions.

About their recent dietary changes, Masai have put on weight and become less healthy as they have urbanized. I've also heard anecdotally that even the rural ones have poor teeth now, a sure sign of a bad quality industrially processed diet. In the early 1900s, it is well documented that they had nearly flawless teeth.

Here are some references for the diet/health decline if you're interested:

Day J et al. Atherosclerosis. 23:357-361. 1976

Christensen DL et al. Ann Hum Biol. 35(2):232-49. 2008. (I could only get my hands on the abstract of this one).

Anonymous said...

This does not surprise me. Looking at obese and morbidly obese people, I think that simply eating a lot of junk food alone cannot explain the unnatural growth. There must be things in the food that are messing with the endocrine system, causing abnormal appetites and weight gain. Fat cells themselves are part of the endocrine system, churning out and responding to the body's hormones. It seems that beyond a certain point, the body spins out of control, and permanent weight loss becomes extremely difficult.

randyfeingersh said...

Hi Stephen,

I was disappointed in your response to my criticism of your analysys of the Mann paper.

You didn't deal with any of the issue I raiesed and more or less just repeated the same point you initialed stated.

I really don't want go back and forth on this particular matter, but I feel giving a green light to high saturated fat intake based on this papper is unwarranted and your argument are based on what I believe an unjustified assumption.

I believe you position is the following:

1. Arterial lesions decrease during the Murin period and increase there after by a highly significant degree.

2. Since during the Murin period the diet is know to be meat, blood and high fat milk products, there must be a noxious agenet introduced after the Murin period that is causing the lesions. Since this foods are available this must be what's causing the increase and most likely these food stuffs carbs and transfat.

My first objection is your assumption the the difference in occurance in arterial lesion is significantly increased after the Murin period.

You state the following:
Stephan Writes:

"The second point is that the atherosclerosis was vastly elevated in vessels of post-Muran Masai as compared to Muran. The data do not follow a gradual slope, they are practically binary. Not just one measure, but three: fibrosis, sudanophilia and total cholesterol. Compare the sudanophilia between 35 yo and 45 yo. It more than doubles. Furthermore, it declines steadily from 15 to 35 years old, exactly the period during which they are Muran. The cholesterol result is undoubtedly statistically significant because the numbers are large. It rises in a very abrupt fashion after the Masai stop eating a diet of pure milk, meat and blood."

The problem is the authors of the paper take the counter view, ie - there is not a significant increase in arterial lesions after the Murin period or decrease during the Murin (realative to the pre Murin period).
Here's a quote from the paper:

"While there is a suggestion
of a decrease of sudanophilia with age from ages 10 through 30, this is not statistically supportable with the variance encountered
within these age groups. Neither was it possible to show an increase of sudanophilia
after age 30."

Also if the Masai were eating processed food( which wasn't reported) for years after Murin period, why didn't their blood lipids levels change radically. In your last report you showed a how large change was reported after 2 weeks, surely we would have seen a large change from a lifetime of eating this "mystery food" that's could be obtained from Indians in the area (even though it hasn't been reported)

I'd also like to reiterate what Mann thought was the most "stricking feature" of the paper:

I quote from the paper:

"It is remarkable, however, that
this degree of sudanophilia is found in a population where cholesteremia averages
125 mg per cent."

Mann makes an even stronger declaration latter when he says:

"The most striking thing about the Masai data is the extent of arterial lesions in a
population with consistently low levels of cholesteremia."

Mann is well aware that low cholesterail levels are associated with clean arteries with the Masai being a unique counter example.

My point is that in this case at the very least we have very good lipid levels associated with extensive Coranary Disease. Could high saturated fat/low carb diets be producing the same effects in elswhere. I don't know, but this paper leads me to believe it's an appropiate question. Like I said earlier we need imaging studies!!
I know atleast two that have been done and negative results were found with Atkins dieters. Admittiedly these were not the best studies though.

Personally I'd like to have No heart attacks and Clean arteries like the Bantu.

Heres the link to the Bantu autopsy study.

Stephan Guyenet said...


Sorry I let you down.

I'd like to point out that their cholesterol DID go up after the Muran period, just like it did when they were fed the artificial diet. Take a look at fig 12. Furthermore, it was also higher before the Muran period. His numbers are large for those measurements, so it is undoubtedly significant.

We will indeed see if low-carbohydrate diets improve CVD risk or not. I'm not as interested in imaging as I am in CVD incidence and mortality, however. Especially total mortality. That will be the true measure of LC's efficacy. The preliminary findings are very encouraging. It certainly works for fat loss. I'm not betting the farm on it just yet, because I can't imagine the standard American diet minus carbohydrate will cure all afflictions.

Keep in mind that the Bantu ate a wide variety of insects. That's a point that's often overlooked. Insects are where they got their fat-soluble animal vitamins like preformed A and K2 (MK-4 isoform). Without those critical nutrients, a vegetarian will fall short of the Bantu's health.

Chris said...

You may be interested in more Masai stuff:

Stephan Guyenet said...

Thanks Chris. I actually posted on that study a while back:

Here's a summary: "Crap, our study showed that the people who eat the most saturated fat are the healthiest, what are we going to do? Look for another explanation"

. said...

Some reasons why primitive people have lower/lowered cholesterol than people in industrialised societies:

Inflammation and infection do not promote arterial aging and cardiovascular disease risk factors among lean horticulturalists

Blood lipids, infection and inflammatory markers in the Tsimane of Bolivia. American Journal of Human Biology